Welcome to the World Factory (Kintsugi Space World Building Thread)

Ways To Make A Planet Orbiting A Red Dwarf Habitable
1. Make it a double planet-this gives you two worlds of roughly the same size, both ignoring their star to face towards their common center of mass, preventing them from getting tidelocked to their star. Day/night cycles will be present but weird-there will be a huge, bright, possibly-living world in the night sky, and sometimes the day sky.

2. Give it a very elliptical orbit and a thickish atmosphere. When it's close to its star, it'll warm up. When it's far from its star, it'll cool down. Result: short, hot summers and long, cool winters-synchronized planetwide. Livable, though.

3. Who says it has to be Earth-sized? Make it very big and not as dense as Earth, so its surface gravity will be lower for its mass-most of the gravity comes from the core and its atmosphere will be thick and richer in things like helium and hydrogen than ours. That will greenhouse it warmer-and the warmth from its hot mantle and core will also heat it up a little, as well as prompting vulcanism to put CO2 into the atmosphere and seed land so it doesn't become a worldsea. Vulcanism will also bring metals to the surface, counteracting the lower concentrations of metals in the rocks. If it has a moon, tidal heating can warm the core up until the plate tectonics look really weird-like putty in places.

4. Who says it has to be habitable for us and not, say, Europeans? Put it far out-like the Big World above-and let it ice over; beneath the insulating ice, warmed by geothermic heating, there'll be liquid water. You want a thinner ice layer than Europa, ideally; that'll give more sunlight to the surface layers. If there's underwater volcanoes, there may be points where the ice layer was pierced by vulcanism-meaning that there'll be places with both nutrient-rich seafloor and energy-rich sunlight!

5. Who says it has to be a planet? Have a large moon (or two, or three) orbiting a massive gas giant in close-they won't tidelock to their star but rather to the gas giant. The gas giant is also like a heatlamp-these moons can be slightly farther out than they could otherwise be, because they also get appreciable heat energy from their planet.

6. Who says it can't be tidelocked? Give it a thick atmosphere to conduct heat and even out the temperature gradient, stick it a bit farther out than a thinner-aired world would be, and you'd get a hot but livable dayside and a cold livable nightside.

7. Or, alternatively, give it an irregular orbit! Slightly elliptical and with some axial tilt. Such an orbit would result in the sun growing and shrinking while also tracking a figure-8 in the sky. That means that both poles and a large area of non-poles will have at least a little day-night cycle. In fact, the somewhat-Earthly conditions zone would be bigger than the dayside-and the dayside is bigger than the nightside, because of atmospheric lensing!

 

It also should be noted that, in the example of an airmoon above-it doesn't have to have an Earthly atmosphere. I've seen a plausible world model where the author was literally challenging themself to come up with a living world with as little air and water as possible! The secret: Water spreads out, and the moon involved is small and very rugged due to tidal stresses. So seas are still a thing, and its tiny amount of air pools in the valleys.

 

I am planning a story involving aliens, and one thing that I've got is that there's a planet with three or so sapient species where one was magically created.

The other two have different body plans (six limbs vs eight limbs).

So. Creatures coming up from The Sea onto A Land (with two groups of lobefins in different areas of The Sea), creatures coming up from A Sea onto A Land, creatures coming up from A Sea onto The Land, or 8limb creatures coming up from The Sea onto The Land and then one group later losing a limb pair?

ETA: Whichever way affects the animal life...creatures coming up from A Sea, rather than The Sea, would be less affected by things like cross-species disease. There'd also be more variety in animal life-the land would have several phylums of large animal, with different limb numbers. Meanwhile, coming up from The Sea onto A Land would imply that the Land is fragmented, like a hundred Australias with no Pangea in the past. So every continent would be full of Australian surprises, but fliers, boatbuilders, or good swimmers would spread everywhere via island chains.
And then the final option means that almost all life there would have the same, eight-limbed body plan, with the exception of the six-limbed sophont and its close relatives-assuming that those are even still extant.

 

...or I could have the six-limbed guys descended from flying fish, instead of lobefins or really weird crustaceans that got their exoskeleton slowly turned into an endoskeleton.

That could even be recent enough that remain amphibious.
And if I do that, then I can have an entire utterly absurd island ecology, because of a mess of volcanoes popping up and forming Fertile Volcanic Australia except not really because Australia was once connected to another landmass.

So the six-limbed guys will inhabit a land where there's coconut-analogues (coconots!), plants descended from sea plants, and maybe things carried over from other islands by Alien Bird Things relatively recently. Animals on their archipelago will be things descended from aquatics, things that could survive many-month voyages on rafts of vegetation, and insects that could survive being windblown massive distances.

This also means that their wings would be from fish-fins...trying to decide which ones though. Front limb pair and last wing pair? Middle limb pair? Front limb pair, with the tail acting as a third wing?
(The rest of their biology is fleshed out! I made a change late in the design process.)

 

Geography!
Does anyone know a way to generate a world bigger than Earth without having to do it all by hand? Doing it all by hand tends to result in not enough randomness, or too much of an Earthly look. This world has a higher sea level than Earth-a worldsea.

 

Effects of magic on a world!

There's a few ways magic can affect a world. It could be something only sapient beings can manipulate. It can be inherently hostile to life. Or you could have magic that can be used by life, as a form of energy.

Then you can decide where and when magic is a thing. Did magic just suddenly Exist one day recently? If so, there's probably no life that uses it.

If magic is inherently hostile to life, where is it on your world? Wherever it is, there'll probably only be very magic-tolerant life there.

If magic isn't inherently hostile to life and can be used by nonsapient beings, it will almost certainly be used. For example, if possible, they may use magic to lower their effective weight in the air, letting larger animals fly. Or there may be plants using magic the same way our plants use light-there's actually fungi on Earth that can use radiation like that, so even inherently dangerous magic could be useful to these.

If there were plantlike organisms on your world that used magic instead of sunlight, they would probably be able to grow in caves or in the dark forest understory just as easily as in a bright meadow-in fact, possibly easier, due to the lack of competition. As such, caves and the dark forest understory will be just as lush as the light areas of the world.

If magic allows for easy warmth, there'd probably be plants using it to stay warm in the snow-combined with the above, you could put forests on the edges of Antarctica without stretching disbelief too much. Only on the rocky areas, though. The icy areas are just kilometers of ice straight down.

If some animals or plants are inherently magical, magic will likely bioaccluminate (spelling?) in that thing's predators, then in the predators of the predators, and so on.

 

sits in this thread because I already herded wingyl into helping with my planet (Which is a red-giant/white-dwarf orbiter with most of the livable atmosphere in deep chasms)

 

@Starcrossedsky i forgot to tell you about some of the consequences for shallow oceans!
specifically, you get a lot of islands, some in weird geological messes-rift fractures.
the oceans in your chasms don't get as deep as earth's, and won't have as much fetch causing huge waves-smaller boats are safer. shallow-draft catamarans would be a good idea for shipping-they're fast. since there'll be a lake or sea in almost every chasm or cave, lots of cultures would be able to develop boats.

also, you could have lots of chasms that are like australias-although if you have only a very small viable population in an area, culture will suffer. papua new guinea independently developed agriculture, but australia didn't, and tasmanians lost the knowledge on how to build bows and arrows because their population was low enough that it was, in deep time, very likely that everyone who knew how died.

you'll want passes linking some of those chasms, very long chasms, or at least one fertile Deeps the size of a country. or all three.

 

Asking for advice here: Should I move the first species from my worldbuilding thread and put them on the double planets instead of the first planet, filling their role on the first planet with something else?

 

Also! Ice ages!
Those shape our world more than most people think. For a start, permafrost is actually a remnant of the Ice Ages. If Earth hadn't had an Ice Age, there'd be no permafrost. Tundra would mean 'cold prairie'.
Then there's the fact that ice is heavy, and large areas of the planet were deformed by the weight of the ice. Those areas are still lower than they'd otherwise be-Hudson Bay would likely not exist without iceweight lowering the ground in that area.
Also, some areas are still warming up. Even if global warming completely stopped and was then reversed to be as if humans had never existed at all, the Earth would likely warm a little, if it didn't go into a new Ice Age-the northernmost parts of Antarctica would slowly thaw, for example.
And finally, there's the effect it's had on island distribution. Earth's likely island-poor for a planet with this much water and tectonic activity-a great many islands eroded down to sea level (as they tend to do) during the last Ice Age. Then the ice melted and the sea drowned them completely.

 

question: ignoring how Gravity Works, what would a planet be like that's just a shell with all the Bits on the inside of that shell? i.e. hollow earth theory

(maybe its rotating Really Fast and the centripetal force is whats keeping all the Bits where theyre supposed to be?)

 

Either really dark or perpetually daylight, for one thing, depending on whether there's an interior light source.

 

Yep, they've got... well, not passes, but a huge number of cave systems link the various larger chasms. Boats are a pretty big thing, the story actually starts in a seaside town that has a really shallow harbor compared to the one on the other side of their chunk of sea, so they use most shallow-bottom ferries compared to deeper-bottomed ships. (This is on the High Sea which is actually the deeper ocean - the surface level of it is almost a mile higher when measured against universal elevation than the shallower Low Sea, and that's just the regions I've semi-developed.)

 

You'd be able to see the 'horizon' curving slightly upwards around you until it became the sky, rather than curving slightly downwards and hiding things from view.
The internal light source would need shading of some type if there's to be day/night cycles-a ring with a gap, probably.
Nights would still be very bright-as if the moon was the entire sky. Also the clouds of the other side would reflect more light than our actually-somewhat-dark moon. Any ice on the other side would shine like a mirror. You'd be seeing in full colour every night.

 

I remember in an old Larry Niven book about the ringworlds that species thought it was an arch due to the immense size. They could see the arch above them, but the horizon curved so gradually that it seemed flat. Granted, this ringworld was the size of earths orbit. I could see a species in the sphere thinking it was more of a dome, depending on the size.

 

@Starcrossedsky Catamarans seem to have a generally lower draft (bottom) than European-style ships. European-style ships have their advantages, but for fast or low-bottomed you want a cat.

Pacific Islander-style cats have moveable sails-you can pick up the boom and move it to the other end of the boat, allowing you to always have one hull windward and the other leeward unless the wind's directly behind the boat. As such, hulls can specialize-you can have one smaller one, for cargo only, that acts as a counterweight and means that you can pull tighter turns, and a larger hull that can have people and cargo and doesn't move up-and-down nearly as much.

Other cats don't have moveable sails, so they're symmetrical overall and have port/starboard rather than windward/leeward, but they also don't have to be shaped the same at both ends-there can be a blunt end of each hull, allowing for more belowdecks room.

 

I don't know enough about boats for this that's what the second draft is for.

There's definitely enough significantly deep ocean for deep bottom boats, though, I mean, whales.

 

Yup! Deep bottom boats for the deep oceans, catamarans for dashes and shallows.

What's your opinion on the 'should I move this species' question I asked earlier?

 

Eh, no strong opinion, it's up to you!

 

Would a link to NASA's Spinoffs website belong here? There's some really interesting stuff in there.